The generator is the main power source in the vehicle. If it breaks down, the performance of the car is limited only by the capacity of the battery. For self-repair of the generator, you must correctly check it and determine the malfunctions.
Necessary
Ohmmeter with diode test function and high resistance measurement mode
Instructions
Step 1
Check generator stator windings. To do this, attach the ohmmeter probes to the stator slip rings and measure the resistance of the field winding. It should be 5-10 ohms, otherwise there is a break in the winding. Attach the test leads to any slip ring and generator stator. The ohmmeter should show infinitely high resistance. If this is not the case, the excitation winding shorts to ground. Check the generator rotor windings in the same way.
Step 2
Check the diode bridge of the generator. To do this, switch the ohmmeter to the diode test mode and attach the positive probe to the common bus of the auxiliary diodes, and the negative probe to the output of the diode under test. The device should show resistance tending to infinity. Otherwise, the diode is faulty. Swap the tester probes. The measured resistance should be significantly less or close to zero (but not zero). In this way, check each diode separately.
Step 3
Repeat the diode bridge test, applying the positive probe not to the common bus, but to the bridge plate into which the diodes are pressed. This will eliminate the possibility of shorting the diodes to ground.
Step 4
Check voltage regulator. Examine his brushes. Make sure that they are mobile, not damaged and worn (should protrude from the holder by no more than 5 mm), that they are not jammed or wedged. Assemble a circuit from an adjustable voltage current source, a test lamp and a regulator. When connecting the negative terminal of the power supply, connect to the regulator ground, and the positive terminal to the terminal of the device under test. Connect the test lamp to the brushes of the tested device.
Step 5
Apply a voltage of 13 V to the regulator. It should freely pass current (the control lamp should be on). Increase the tension gradually. At a value of 14, 5-15 V, the regulator should stop supplying current to the control lamp. With a gradual decrease in voltage, the test lamp should turn on again at a voltage of 13-13.5 V.
Step 6
Check the generator capacitor. Connect an ohmmeter to its terminals. On a working device, the device will first show a slight resistance, which will rapidly increase until it stabilizes. When the polarity of the instrument is reversed, the reading should change in the same way.
